1. Field of the Invention
The invention relates to a process for reducing the resistivity (i.e., specific resistance) of an electrically conductive layer of molybdenum or a molybdenum alloy.
Electrically conductive layers of molybdenum or a molybdenum alloy for electrical or electronic components are used primarily in applications where, in addition to good electrical conductivity, a good ability of the layer to withstand high temperatures is also important.
In many electrical and electronic components, in addition to the electrically conductive layers, for example in the form of interconnects, in many cases further layers for other functions are also required and are generally deposited on the interconnects at a later stage. Therefore, even the temperatures of up to 450° C. which occur during coating alone result in a high thermal load on the interconnects, so that molybdenum and molybdenum alloys are in widespread use as layer material for the interconnects.
Typical examples for the use of thin films of molybdenum and molybdenum alloys are interconnects in flat panel displays or electrically conductive layers in solar cells.
A problem in this context is that above an elevated atmospheric humidity of 60% relative humidity, molybdenum, even at room temperature, forms surface layers, which consist of compounds comprising approximately 12 atomic % of molybdenum, approximately 75 atomic % of oxygen and approximately 8 atomic % of nitrogen. These surface layers, compared to pure molybdenum, have a considerably higher restivity.
Even if the surface layers are only formed with a relatively small thickness of the order of magnitude of a few nanometers, in the case of thin films the elevated contact resistance means that the sheet resistivity is increased considerably thereby.